thanks for having me. >>> president obama losing his voice. we're going to explain. that's next. >>> the man behind so many of the president's most memorable lines is leaving. our white house correspondent brianna keilar has more now. john favreau. >> reporter: president obama is losing his voice, his chief speech writer, john favreau, is leaving the white house. favs, as he's known around the west wing, has helped write almost every speech since he was a senator. >> the will and the determination of the american people that change this country. yes, we can. >> reporter: from his first run for president. >> we are an american family and we rise or fall together. >> reporter: to obama's november acceptance speech in chicago. favreau was seen working on it in this official white house photo as he was awaiting mitt romney's concession call. he collaborated in all of the state of the union addresses including the one he is set to give next week. favreau met obama in 2004 while he was a 23-year-old staffer on john kerry's presidential campaign. >> out of this long politic